Rotor and Permanent Magnet Motor

Abstract

The present invention discloses a rotor and a permanent magnet motor. The rotor includes an iron core and a magnet slot group. The magnet slot group includes a first magnet slot, a magnet, and a magnetic bridge. Each first magnet slot is correspondingly provided with an air slot. The air slot is disposed on one side clamped by two first magnet slots and is near the corner of the magnet. The first magnet slot includes a first slot wall and a second slot wall. The magnet includes a first end portion and a second end portion. The first end portion is arranged towards the V-shaped opening direction, and the second end portion is arranged towards the V-shaped tip direction. The air slot includes a first air slot near the corner of the first end portion and a second air slot near the corner of the second end portion. Compared with the prior art, the present invention can alleviate the demagnetization effect of the demagnetizing magnetic field on the corners of the magnet, and at the same time, it will not affect the output torque of the permanent magnet motor.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet motors, and particularly to a rotor and a permanent magnet motor. Background Art

[0002] Environmental pollution and energy crisis have promoted the rapid development of the new energy vehicle industry, especially the booming development of the electric vehicle industry. As one of the key actuating components of electric vehicles, the performance of vehicle drive permanent magnet motors is crucial for the performance of the whole vehicle. Due to advantages such as high power density and high efficiency, permanent magnet motors have been widely used in the field of vehicle drive permanent magnet motors. Permanent magnet motors have the advantages of simple structure, small volume, low loss, high efficiency and easy control. In order to improve the power density of the drive system, a permanent magnet motor and a reducer are usually combined to provide driving force for electric vehicles, or a three-in-one assembly in which a permanent magnet motor, a reducer and a permanent magnet motor controller are highly integrated.

[0003] However, due to the special operating conditions of electric vehicles, permanent magnet motors are required to have a high torque density, that is, while requiring a large torque of the permanent magnet motor, it is also necessary to ensure that the permanent magnet motor has a small volume. In the prior art, some will increase the output torque of the permanent magnet motor by increasing the stack height of the permanent magnet motor, but this will also increase the volume of the permanent magnet motor. Others will use high-performance magnetic steel to increase the output torque of the permanent magnet motor, but the high-performance magnetic steel will also increase the cost of the permanent magnet motor, and the high-performance magnetic steel will also cause magnetic circuit saturation, thereby increasing iron loss. At the same time, improving the remanence of the magnetic steel has limited improvement on the torque performance. When reaching a certain level, the torque performance of the permanent magnet motor cannot be further improved.

[0004] At the same time, in the prior art, when the amount of magnetic steel is the same, the thickness of the rotor magnetic bridge will affect the magnetic leakage of the magnetic steel. A larger magnetic bridge thickness will increase the magnetic leakage, thereby reducing the output torque of the permanent magnet motor. Therefore, in order to obtain a larger output torque, it is necessary to minimize the thickness of the magnetic bridge as much as possible. However, too small a magnetic bridge thickness will exacerbate the demagnetization state of the magnetic steel of the permanent magnet motor. This is mainly because a smaller magnetic bridge thickness restricts the direction of the demagnetizing magnetic field, causing the demagnetizing magnetic field to concentrate on passing through the magnetic steel of the permanent magnet motor, thereby exacerbating the demagnetization state of the magnetic field. If the demagnetization rate of the magnetic steel is to be reduced, it is necessary to increase the coercivity of the magnetic steel, which in turn requires an increase in the amount of rare earth, thus increasing the cost of the magnetic steel and further increasing the total cost of the permanent magnet motor. It is also possible to increase the amount of magnetic steel to reduce the demagnetization rate of the magnetic steel and ensure the stability of the permanent magnet motor. However, the increase in the amount of magnetic steel will also increase the cost of the permanent magnet motor, and the increase in the amount of magnetic steel will also deteriorate the mechanical strength of the rotor under the action of centrifugal force.

[0005] Therefore, it is necessary to design a rotor with excellent demagnetization resistance to ensure the output torque of the permanent magnet motor without increasing the volume and cost. Summary of the Invention

[0006] The present invention provides a rotor and a permanent magnet motor, which can design a rotor with excellent demagnetization resistance without increasing the volume and cost and ensuring the output torque of the permanent magnet motor.

[0007] The technical solution adopted by the present invention is: a rotor, including an iron core and a magnetic steel groove group. The magnetic steel groove group includes two first magnetic steel grooves distributed in a V shape with the tip direction of the V shape facing the center of the iron core. A magnetic steel with a rectangular cross-section is arranged in the first magnetic steel groove. A magnetic bridge is provided at the V-shaped tip between the two first magnetic steel grooves. An air groove is correspondingly arranged for each first magnetic steel groove. The air groove is arranged on one side clamped by the two first magnetic steel grooves and near the corner of the magnetic steel.

[0008] Further, the first magnetic steel groove includes a first groove wall and a second groove wall extending from the tip of the V shape to the opening direction. The magnetic steel is embedded between the first groove wall and the second groove wall. The first groove wall is arranged on one side clamped by the two first magnetic steel grooves. The magnetic steel includes a first end and a second end perpendicular to the first groove wall. The first end is arranged towards the V-shaped opening direction, and the second end is arranged towards the V-shaped tip direction. The air groove includes a first air groove, and the first air groove is near the corner of the magnetic steel at the first end.

[0009] Further, the minimum vertical distance D1 between the groove wall of the first air groove and the first groove wall is 0.2 mm to 0.3 mm; the vertical distance D2 between the center of the first air groove and the first end is 0.2 mm to 0.3 mm; the first magnetic steel groove further includes a third groove wall connected to the first groove wall and deflecting towards the inner side of the angle between the two first magnetic steel grooves. The minimum vertical distance D3 between the groove wall of the first air groove and the third groove wall is 0.2 to 0.3 mm.

[0010] Further, the air groove further includes a second air groove, and the second air groove is near the corner of the magnetic steel at the second end.

[0011] Further, the minimum vertical distance D4 between the groove wall of the second air groove and the first groove wall is 0.2 mm to 0.4 mm; the vertical distance D5 between the center of the second air groove and the second end is 0.6 mm to 0.8 mm.

[0012] Further, the first air groove and the second air groove are elliptical.

[0013] Further, the length of the major axis L1 of the first air groove is 0.5 mm to 0.6 mm, the length of the minor axis L2 is 0.3 mm to 0.4 mm, and the angle A between the major axis and the first groove wall is 20° to 35°; the length of the major axis L3 of the second air groove is 0.6 mm to 0.7 mm, the length of the minor axis L4 is 0.3 mm to 0.4 mm, and the angle B between the major axis and the first groove wall is 20° to 35°.

[0014] Further, the magnet groove group further includes two second magnet grooves distributed in a V shape with the tip direction of the V shape facing the center of the iron core, and the second magnet grooves are arranged on one side of the first magnet groove away from the center of the iron core.

[0015] Further, the included angle between the two first magnet grooves is less than 15°.

[0016] A permanent magnet motor, which includes the rotor described above.

[0017] Compared with the prior art, the present invention sets a first convex portion in the magnet groove of the rotor core. The setting of the first convex portion can play a role in guiding the flow. When the permanent magnet motor is in the most severe demagnetization state, the first convex portion can guide the demagnetization magnetic field, relieve the demagnetization effect of the demagnetization magnetic field on the corners of the magnet, and at the same time will not affect the output torque of the permanent magnet motor. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic structural diagram of the magnet groove on the iron core in the present invention;

[0020] Figure 2 It is an enlarged schematic structural diagram of A in the present invention;

[0021] Figure 3 It is an enlarged schematic structural diagram of B in the present invention. Detailed Embodiments

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the following further details the present invention with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] In this application, the rotor includes an iron core formed by stacking multiple laminations. The iron core includes a plurality of magnetic poles distributed along its circumference, and each magnetic pole includes a set of magnetic steel slots.

[0024] As Figure 1 shown, taking one set of magnetic steel slots of the iron core as an example for illustration, the set of magnetic steel slots includes two first magnetic steel slots 1 and two second magnetic steel slots 2.

[0025] Among them, the two first magnetic steel slots 1 are symmetrically distributed in a V shape, and the tip of the V shape formed by the two first magnetic steel slots 1 extends towards the center direction of the iron core, with the opening facing the outside of the iron core. A first magnetic bridge 11 is formed between the ends of the two first magnetic steel slots 1 at the tip. A magnetic steel 3 is embedded in each first magnetic steel slot 1, and the magnetic steel 3 is fixed at the middle position of the first magnetic steel slot 1 by means of glue.

[0026] Furthermore, the two second magnetic steel slots 2 are also distributed in a V shape. The second magnetic steel slots 2 are arranged above the first magnetic steel slots 1, that is, on the outer side in the radial direction of the first magnetic steel slots 1. The tip of the V shape formed by the two second magnetic steel slots 2 extends towards the center direction of the iron core, with the opening facing the outside of the iron core. A second magnetic bridge 21 is formed between the ends of the two second magnetic steel slots 2 at the tip. A magnetic steel 3 is also embedded in each second magnetic steel slot 2, and the magnetic steel 3 is fixed at the middle position of the second magnetic steel slot 2 by means of glue. At the same time, there is a certain interval between the first magnetic steel slots 1 and the second magnetic steel slots 2. The first and second magnetic steel slots are both arranged along the quadrature magnetic circuit of the permanent magnet motor, which helps to reduce the influence of the magnetic steel slots on the quadrature inductance of the permanent magnet motor, and thus ensures the reluctance torque of the permanent magnet motor, which is beneficial to alleviating the saturation of the quadrature magnetic circuit and increasing the utilization rate of the reluctance torque. In addition, the certain distance between the two layers of magnetic steel is also beneficial to alleviating the demagnetization effect of the demagnetizing magnetic field on the magnetic steel.

[0027] Preferably, the included angle between the two first magnetic steel slots 1 is less than 15°, which can ensure the utilization rate of the reluctance torque.

[0028] Further, the first magnet groove 1 includes a first groove wall 15 and a second groove wall 16 extending from the tip of the V shape to the opening direction. The first groove wall 15 and the second groove wall 16 are arranged opposite to each other. Among them, the first groove wall 15 is arranged inside the opening of the V shape, that is, on the side clamped by two first magnet grooves 1, while the second groove wall 16 is arranged outside the opening of the V shape; and the magnet 3 is fitted between the first and second groove walls. The two side parts of the magnet 3 are fitted with the first groove wall 15 and the second groove wall 16. The magnet 3 further includes a first end 31 and a second end 32. The first and second ends are both arranged at an angle with the first and second magnets, which is perpendicular in this embodiment. The first end 31 is arranged towards the opening direction of the V shape, while the second end 32 is arranged towards the tip direction of the V shape; and the first magnet groove 1 further includes a third groove wall 17. The third groove wall 17 is connected to the first groove wall 15, and the third groove wall 17 deflects a certain angle towards the inner side of the angle between the two first magnet grooves 1. The connection part of the third groove wall 17 and the first groove wall 15 is arranged near the magnet 3.

[0029] In the rotor of the present application, multiple groups of air grooves 4 are provided. Each group of air grooves 4 is arranged in one-to-one correspondence with the first magnet groove 1, that is, a group of corresponding air grooves 4 is arranged near each first magnet groove 1. The air grooves 4 are arranged on the side clamped by two first magnet grooves 1, and the air grooves 4 are arranged at the corners near the magnet 3. Under the action of the air grooves 4, the demagnetization resistance performance of the magnet 3 under the most severe demagnetization working condition is improved, the demagnetization rate is significantly reduced, the output torque is guaranteed to a certain extent, and the torque ripple is also relatively small.

[0030] Further, as Figure 2 shown, each group of air grooves 4 includes a first air groove 41 and a second air groove 42; among them, taking the first air groove 41 as an example, the first air groove 41 is arranged at the upper corner near the magnet 3 in the first magnet groove 1, that is, near the corner of the magnet 3 at the first end 31. The minimum vertical distance D1 between the groove wall of the first air groove 41 and the first groove wall 15 is 0.2 mm to 0.3 mm. The vertical distance D2 between the center of the first air groove 41 and the first end 31 is 0.2 mm to 0.3 mm. And the minimum vertical distance D3 between the groove wall of the first air groove 41 and the third groove wall 17 is 0.2 mm to 0.3 mm.

[0031] Such a design avoids the problem that the first air groove 41 is too close to the groove wall of the first magnet groove 1, which affects the mechanical strength of the rotor and increases the difficulty of core production and processing. And it avoids the problem that if the first air groove 41 is too far from the groove wall of the first magnet groove 1, it will increase the magnetic leakage of the magnet 3, which is not conducive to improving the working point of the magnet at the corner of the magnet, resulting in a reduction in the demagnetization resistance ability of the magnet 3.

[0032] Further, as Figure 3As shown, the second air groove 42 is arranged at the corner near the second end 32 of the magnet 3 in the first magnet groove 1, and the minimum vertical distance D4 between the groove wall of the second air groove 42 and the first groove wall 15 is 0.2 mm to 0.4 mm, and the vertical distance D5 from the center of the second air groove 42 to the second end 32 is 0.6 mm to 0.8 mm.

[0033] Such a design avoids the problem that the second air groove 42 is too close to the groove wall of the first magnet groove 1, which affects the mechanical strength of the rotor and increases the difficulty of core production and processing. At the same time, it avoids the problem that if the second air groove 42 is too far from the groove wall of the first magnet groove 1, the magnetic leakage of the magnet 3 will increase, which is not conducive to improving the working point of the magnet at the corner of the magnet, resulting in a decrease in the demagnetization resistance of the magnet 3.

[0034] Preferably, the first air groove 41 and the second air groove 42 in this application are both arranged in an oval shape, because the oval air groove has a more obvious effect on suppressing the demagnetization of the magnet compared with other shapes.

[0035] Furthermore, the first air groove 41 is oval, and the length of its major axis L1 is 0.5 mm to 0.6 mm, the length of its minor axis L2 is 0.3 mm to 0.4 mm, and the angle A between the major axis and the first groove wall 15 is 20° to 35°; the second air groove 42 is oval, the length of its major axis L3 is 0.6 mm to 0.7 mm, the length of its minor axis L4 is 0.3 mm to 0.4 mm, and the angle B between the major axis and the first groove wall 15 is 20° to 35°; such a setting makes the size of the air groove just right, avoiding the size of the air groove being too small, so that the demagnetization rate near the corner of the magnet cannot be effectively alleviated, and avoiding the size of the air groove being too large, which affects the mechanical strength at this place and leads to the problem of low output torque of the permanent magnet motor. At the same time, the relative position between the oval air groove and the magnet groove can achieve the best demagnetization resistance performance.

[0036] Furthermore, the shape of the air groove can also be set as a circle or other irregular shapes.

[0037] This application also proposes a permanent magnet motor, and the permanent magnet motor includes the rotor proposed in this application.

[0038] After testing, a permanent magnet motor with two groups of rotors having the same number and V-shaped settings was used for a comparative test. One group was a traditional permanent magnet motor with a conventional air groove design, and the other group was a permanent magnet motor with the air groove design of this application. The demagnetization of the magnet under the same harsh conditions is as follows:

[0039] Traditional permanent magnet motor: The demagnetization rates of the magnets in the left and right first magnet grooves are 2.33% and 2.37% respectively, and the demagnetization positions of the magnets are mainly concentrated at the corners;

[0040] The permanent magnet motor of the present application: the demagnetization rates of the magnets in the two first magnet slots on the left and right are 1.89% and 1.91% respectively, the demagnetization positions are concentrated at the corners, and the demagnetization area is reduced.

[0041] After test comparison, under the same conditions, the operating conditions of the traditional permanent magnet motor and the permanent magnet motor of the present application are as follows: for the traditional motor, the average torque is 220.1183 Nm and the torque ripple is 3.69%; for the motor of the present application, the average torque is 220.1039 Nm and the torque ripple is 3.66%.

[0042] As can be seen from the above, when the demagnetization rate of the magnet is greatly reduced, the output torque of the permanent magnet motor in the present application is basically the same as that of the traditional permanent magnet motor, and the output ripple is the same. The setting of the present application has quite excellent practical value.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A rotor, comprising an iron core and a magnet slot group, wherein the magnet slot group includes two first magnet slots distributed in a V shape with the tip direction of the V shape facing the center of the iron core. A magnet with a rectangular cross-section is arranged in each of the first magnet slots, and a magnetic bridge is provided at the V-shaped tip between the two first magnet slots. It is characterized in that, Each of the first magnet grooves is correspondingly provided with an air groove, the air groove is arranged on one side clamped by two of the first magnet grooves, and the air groove is near the corner of the magnet; The first magnet groove includes a first groove wall and a second groove wall extending from the tip of the V shape to the opening direction, the magnet is embedded between the first groove wall and the second groove wall, the first groove wall is arranged on one side clamped by two of the first magnet grooves, the magnet includes a first end and a second end perpendicular to the first groove wall, the first end is arranged towards the V-shaped opening direction, and the second end is arranged towards the V-shaped tip direction; The air groove includes a first air groove and a second air groove, the first air groove is near the corner of the first end of the magnet, and the second air groove is near the corner of the second end of the magnet; The first air groove and the second air groove are elliptical, the length of the major axis L1 of the first air groove is 0.5 mm to 0.6 mm, the length of the minor axis L2 is 0.3 mm to 0.4 mm, and the angle A between the major axis and the first groove wall is 20° to 35°; the length of the major axis L3 of the second air groove is 0.6 mm to 0.7 mm, the length of the minor axis L4 is 0.3 mm to 0.4 mm, and the angle B between the major axis and the first groove wall is 20° to 35°; The magnet groove group further includes two second magnet grooves distributed in a V shape with the tip direction of the V shape facing the center of the iron core, and the second magnet grooves are arranged on the side of the first magnet grooves away from the center of the iron core.

2. The rotor according to claim 1, characterized in that, The minimum vertical distance D1 from the groove wall of the first air groove to the first groove wall is 0.2 mm to 0.3 mm; The vertical distance D2 from the center of the first air groove to the first end is 0.2 mm to 0.3 mm; the first magnet groove further includes a third groove wall connected to the first groove wall and deflected towards the inner side of the angle between the two first magnet grooves, and the minimum vertical distance D3 from the groove wall of the first air groove to the third groove wall is 0.2 to 0.3 mm.

3. The rotor according to claim 1, characterized in that, The minimum vertical distance D4 from the groove wall of the second air groove to the first groove wall is 0.2 mm to 0.4 mm; the vertical distance D5 from the center of the second air groove to the second end is 0.6 mm to 0.8 mm.

4. The rotor according to claim 1, characterized in that, The angle between the two first magnet grooves is less than 15°.

5. A permanent magnet motor, characterized in that, The permanent magnet motor includes a rotor as described in any one of claims 1 to 4.

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